/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.feilong.lib.net.io;

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

/***
 * The Util class cannot be instantiated and stores short static convenience
 * methods that are often quite useful.
 *
 *
 * @see CopyStreamException
 * @see CopyStreamListener
 * @see CopyStreamAdapter
 ***/
public final class Util{

    /**
     * The default buffer size ({@value}) used by
     * {@link #copyStream copyStream }
     * and by the copyReader/copyStream methods if a zero or negative buffer size is supplied.
     */
    public static final int DEFAULT_COPY_BUFFER_SIZE = 1024;

    // Cannot be instantiated
    private Util(){
    }

    /***
     * Copies the contents of an InputStream to an OutputStream using a
     * copy buffer of a given size and notifies the provided
     * CopyStreamListener of the progress of the copy operation by calling
     * its bytesTransferred(long, int) method after each write to the
     * destination. If you wish to notify more than one listener you should
     * use a CopyStreamAdapter as the listener and register the additional
     * listeners with the CopyStreamAdapter.
     * <p>
     * The contents of the InputStream are
     * read until the end of the stream is reached, but neither the
     * source nor the destination are closed. You must do this yourself
     * outside of the method call. The number of bytes read/written is
     * returned.
     *
     * @param source
     *            The source InputStream.
     * @param dest
     *            The destination OutputStream.
     * @param bufferSize
     *            The number of bytes to buffer during the copy.
     *            A zero or negative value means to use {@link #DEFAULT_COPY_BUFFER_SIZE}.
     * @param streamSize
     *            The number of bytes in the stream being copied.
     *            Should be set to CopyStreamEvent.UNKNOWN_STREAM_SIZE if unknown.
     *            Not currently used (though it is passed to {@link CopyStreamListener#bytesTransferred(long, int, long)}
     * @param listener
     *            The CopyStreamListener to notify of progress. If
     *            this parameter is null, notification is not attempted.
     * @param flush
     *            Whether to flush the output stream after every
     *            write. This is necessary for interactive sessions that rely on
     *            buffered streams. If you don't flush, the data will stay in
     *            the stream buffer.
     * @return number of bytes read/written
     * @throws CopyStreamException
     *             If an error occurs while reading from the
     *             source or writing to the destination. The CopyStreamException
     *             will contain the number of bytes confirmed to have been
     *             transferred before an
     *             IOException occurred, and it will also contain the IOException
     *             that caused the error. These values can be retrieved with
     *             the CopyStreamException getTotalBytesTransferred() and
     *             getIOException() methods.
     ***/
    public static long copyStream(
                    InputStream source,
                    OutputStream dest,
                    int bufferSize,
                    long streamSize,
                    CopyStreamListener listener,
                    boolean flush) throws CopyStreamException{
        int numBytes;
        long total = 0;
        byte[] buffer = new byte[bufferSize > 0 ? bufferSize : DEFAULT_COPY_BUFFER_SIZE];

        try{
            while ((numBytes = source.read(buffer)) != -1){
                // Technically, some read(byte[]) methods may return 0 and we cannot
                // accept that as an indication of EOF.

                if (numBytes == 0){
                    int singleByte = source.read();
                    if (singleByte < 0){
                        break;
                    }
                    dest.write(singleByte);
                    if (flush){
                        dest.flush();
                    }
                    ++total;
                    if (listener != null){
                        listener.bytesTransferred(total, 1, streamSize);
                    }
                    continue;
                }

                dest.write(buffer, 0, numBytes);
                if (flush){
                    dest.flush();
                }
                total += numBytes;
                if (listener != null){
                    listener.bytesTransferred(total, numBytes, streamSize);
                }
            }
        }catch (IOException e){
            throw new CopyStreamException("IOException caught while copying.", total, e);
        }

        return total;
    }

    /**
     * Closes the object quietly, catching rather than throwing IOException.
     * Intended for use from finally blocks.
     *
     * @param closeable
     *            the object to close, may be {@code null}
     * @since 3.0
     */
    public static void closeQuietly(Closeable closeable){
        if (closeable != null){
            try{
                closeable.close();
            }catch (IOException e){
                // Ignored
            }
        }
    }

    /**
     * Closes the socket quietly, catching rather than throwing IOException.
     * Intended for use from finally blocks.
     *
     * @param socket
     *            the socket to close, may be {@code null}
     * @since 3.0
     */
    public static void closeQuietly(Socket socket){
        if (socket != null){
            try{
                socket.close();
            }catch (IOException e){
                // Ignored
            }
        }
    }
}
